My faves (so far)
Training: The Idiot's Guide to Positive Dog Training by Pam Dennison
The Power of Positive Dog Training by Pat Miller
The Puppy Whisperer by Paul Owens
Behaviour and understanding your dog:
Patricia McConnell's "The Other End of the Leash" and "For the Love of a dog".
Jean Donaldson's "The Culture Clash"
Brenda Aloff's "Canine Body Language: a Photographic Guide"
Turid Rugaas' "On Talking Terms with Dogs: Calming Signals"
I also have favourites for "special needs" dogs...Leash reactivity, scientific behavior studies, fearful dogs etc. If you want a list I'd be happy to recommend more. LOL